Dual Cell System Research Articles

Decoupling Charge Carrier Electroreduction and Enzymatic CO2 Conversion to Formate Using a Dual-Cell Flow Reactor System.

With an efficient atom economy, low activation energy, and valuable applications for fuel cells and hydrogen storage, formic acid (FA) is a useful fuel product to convert CO2 and reduce emissions. Although metal catalysts are typically used for this conversion, unwanted side reactions remain a concern, particularly when products are attempted to be recovered long-term. In this study, an enzymatic catalyst is used to enable the selective conversion of CO2 to FA, as a formate ion. A dual-cell flow reactor system is used to first reduce a charge mediator electrochemically (reduction cell), which then activates a catalyst to selectively convert CO2 to formate (production cell). This approach minimizes enzyme degradation by avoiding direct contact with increased voltages and improves the quantity of formate produced. The system produced 25 mM of formate and reached over 50% Coulombic efficiency. The larger volume of this dual-cell system increases the quantity of formate produced beyond that of a batch cell. Additional design configurations are employed, including a pH control pump to maintain catalyst activity and a packed bed reactor to improve contact of the charge carrier with the catalyst. Both configurations retained higher production and efficiency long-term (∼168 h). The results highlight the challenges of developing a system where many parameters play a role in optimizing performance. Nevertheless, the ability of the system to produce formate from CO2 demonstrates the potential to improve upon this configuration for a variety of electrochemical CO2 conversion applications.

Electrochemically-driven dosing of iron (II) for autonomous electro-Fenton processes with in situ generation of H2O2

Reliance of Fenton processes to hazardous chemicals diminishes the range of niche applications of this highly efficient advanced oxidation process due to risks associated to transport, storage, and handling of chemicals. In this work, an alternative approach towards independent Fenton systems integrating (1) per demand in situ production of H2O2 from oxygen cathodic reduction and (2) electrochemically-driven iron (II) dosing system is explored as a novel strategy. For this purpose, a dual-cell system was designed to fulfill individual current needs of both processes while avoiding excessive iron sludge production observed in peroxicoagulation treatments. Experimental results indicate high reproducibility and resilience of the proposed dual-cell electro-Fenton system, which attained complete organic methylene blue dye decolorization in 80 ​min of treatment and over 80% mineralization in only 120 ​min of electro-Fenton treatment. These results showcase a new approach that opens alternative pathways for possible implementation of low-physical footprint electro-Fenton systems as point-of-entry treatments or even to treat effluents of small and mid-sized industries.

Differential photoacoustic spectroscopic (DPAS)-based technique for PM optical absorption measurements in the presence of light absorbing gaseous species

ABSTRACTIn this study, we developed an optical monitor to measure light absorption from particulate matter (PM) at 532 nm using a differential photoacoustic absorption spectroscopic (DPAS) technique. The dual-cell system is capable of measuring the photoacoustic signals due to light absorption of total PM and gaseous samples and that of gaseous samples, separately. The resulting differential photoacoustic signal can be used to determine the light absorption purely from the PM species. This measurement method eliminates the interferences from the light-absorbing gaseous species as well as the surrounding low-frequency background acoustic noises. Photoacoustic signals of the DPAS monitor were calibrated with the NO2 gas standards, varying from 100 to 250 parts per billion (ppb). Based on an Allan analysis, a detection sensitivity (2σ) of 0.68 Mm−1 can be achieved in 100 s data acquisition. Using the Jet Burner Test Stand (JBTS) facility at the United Technologies Research Center (UTRC), we measured light ab...

Long-Term Morphological Changes in Simulated Supercells Following Mergers with Nascent Supercells in Directionally Varying Shear

Abstract Mergers involving supercells remain a challenge for severe thunderstorm forecasting. In this study, mergers between supercells and ordinary cells (e.g., cells forming in a similar environment but too young to be fully developed supercells) are investigated. A series of numerical experiments are performed using an idealized, homogenous environment supportive of cyclonically rotating, right-moving supercells. Warm bubbles are introduced at different times, resulting in two storms of different maturity; their placement is used to control the location of the merger and the relative maturity of the second storm. Simplified conceptual models for the long-term outcomes of mergers are developed. In the simplest mode of merger, outflow from the new cell cuts off inflow to the original. If the new cell’s cold pool is not sufficiently strong to cut off the inflow to the original cell, the minimum separation of the updraft maxima during the merger becomes a key controlling factor in the outcome. If it is less than 10 km, an updraft collision occurs, resulting in a classic supercell. If it is greater than 20 km and the new cell merges into the original cell’s forward flank, a dual-cell system results. If it is between 10 and 20 km, the enhanced precipitation produced during the merger leads to a cold pool surge and an updraft bridge, joining the original updrafts and developing into either a small bow echo (with forward-flank mergers) or a supercell on the classic high-precipitation spectrum (with rear-flank mergers), depending on the distribution of precipitation in the merging system.

One-pot immunotoxicity – Dual cell system communication assays for in vitro assessment of inflammation

It’s quite necessary to fabricate reproducible and uniform surface-enhanced Raman scattering (SERS) composite substrate with high enhancement factor simply. Therefore, in this work, in order to obtain the SERS substrates with optimized size and gap, Ag films with different thickness deposited by magnetron sputtering and following annealing are performed. The results both elucidate the function relationship between the size, gap of nanoparticles and the thickness of Ag films, and ascertain the optimized parameters for silver nanoparticles on the basis of finite-difference time-domain simulation, the SERS signal using graphene and Rhodamine 6G (R6G) as probe molecules for Ag-NPs/Si substrates. Moreover, our findings highlight the Ag NPs with optimized size and gap as SERS substrates present high reproducibility and uniformity.

Effects of magnetic heat treatment on microstructure and hydrogen permeation properties of Nb-Ti-Ni alloy membranes

In this paper, effects of magnetic heat treatment (MHT) on structure and hydrogen permeation properties of Nb49Ni25Ti26 alloy membrane have been investigated. XRD and SEM were employed to characterize its phases and microstructure. Also, hydrogen diffusion coefficients (DH) of the alloy membrane were measured in Devanathan-Stachurski (D-S) dual-cell system. The results indicate that MHT-treated alloys still maintain their two-phase structure, consisting of the primary bcc-Nb (Ni, Ti) solid solution phase and (bcc-Nb(Ni, Ti) + β2-NiTi) eutectic phase, with their DH increment after MHT at 0° and 90° respectively. The maximum value of DH is 6.3822 × 10−9 H2 m2/s for the alloy membrane treated by MHT at 0° angle (magnetic field direction is parallel to membrane surface), the increase of DH is possibly due to the grain orientation, and the formation of smaller solid solution phase region with higher specific area. Such results suggest that reasonable MHT benefits to the improvement of hydrogen permeation properties of Nb49Ni25Ti26 alloy membrane.

Continuous production of high-purity fructooligosaccharides and ethanol by immobilized Aspergillus japonicus and Pichia heimii

High-purity fructooligosaccharides (FOS) were produced from sucrose by an innovative process incorporating immobilized Aspergillus japonicus and Pichia heimii cells. Intracellular FTase of A. japonicus converted sucrose into FOS and glucose, and P. heimii fermented glucose mainly into ethanol. The continuous production of FOS was carried out using a tanks-in-series bioreactor consisting of three stirred tanks. When a solution composed of 1 g L(-1) yeast extract and 300 g L(-1) sucrose was fed continuously to the bioreactor at a dilution rate of 0.1 h(-1), FOS at a purity of up to 98.2 % could be achieved and the value-added byproduct ethanol at 79.6 g L(-1) was also obtained. One gram of sucrose yielded 0.62 g FOS and 0.27 g ethanol. This immobilized dual-cell system was effective for continuous production of high-purity FOS and ethanol for as long as 10 days.

인지 네트워킹 기반 중첩 융합 네트워크에서 이중 가상 셀 운영방안의 성능분석

데이터 트래픽의 증가와 더불어 인지 기반 중첩 융합 네트워크 환경 하에서의 서비스 성능이 중요한 이슈로 떠오르고 있다. 이에 따라 다양한 이종 네트워크(HetNet)가 결합된 환경 하에서 주변상황의 인지 기능을 활용하는 이중 가상 셀의 구성과 특징에 대해 살펴보고 자원의 효과적 활용에 적합한 개별 이종 네트워크의 특성분석과 특성을 반영하는 시스템측면의 최적화를 고려하여 성능측면의 분석을 다루고자 한다. 이를 위해 가상 이중 셀 시스템의 구성과 운영이 필수적으로 요구된다. 본 논문에서는 기지국의 소형화와 지능화가 진행됨에 따른 활용도 측면의 성능을 분석하였다. 고려하는 시스템은 유용한 가상의 신호를 찾을 수 있는 능력을 활용하여 가상의 이중 셀을 구성하고 고속이동에 따른 무선링크에서의 성능열하를 방지하고 고속의 데이터 전송을 위한 시-공간 트렐리스 코드를 적용한 시스템의 성능을 분석하여 그 유용성에 대해서 시뮬레이션을 통하여 정량적인 분석결과를 얻었다. 이를 바탕으로 다양한 파라메터가 주어진 환경 하에서 전체 시스템에 어떤 영향를 미치는지를 해석하고 고려하는 시스템의 특징을 고찰하였다. With the fast growing data traffic, the performance of the convergent overlay network environment under the cognitive networking environment is crucial for the implementation of the efficient network structure. In order to achieve high capacity and reliable link quality in wireless communication of the overlay convergent networks with the cognitive networking based on the advanced capability of the mobile terminal, a Distributed Wireless Communication System (DWCS) can provide the capability of ambient-aware dual cell system's operation. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. One is the Active Virtual Cell which exists for user's actual data traffic and the other is the Candidate Virtual Cell which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. The considered system constructs DVC by using cognitive ability of finding useful virtual signals. Also, for multi-user high-rate data transmission, the DWCS system exploits Space-Time Trellis Codes. The effects of changing environments on the system performance has been investigated thereafter.

Isolation of dimorphic chloroplasts from the single-cell C4 species Bienertia sinuspersici.

Three terrestrial plants are known to perform C4 photosynthesis without the dual-cell system by partitioning two distinct types of chloroplasts in separate cytoplasmic compartments. We report herein a protocol for isolating the dimorphic chloroplasts from Bienertia sinuspersici. Hypo-osmotically lysed protoplasts under our defined conditions released intact compartments containing the central chloroplasts and intact vacuoles with adhering peripheral chloroplasts. Following Percoll step gradient purification both chloroplast preparations demonstrated high homogeneities as evaluated from the relative abundance of respective protein markers. This protocol will open novel research directions toward understanding the mechanism of single-cell C4 photosynthesis.

Electrogenerative leaching for sphalerite-MnO 2 in the presence of Acidithiobacillus thiooxidans

A dual cell system was used to study the electrogenerative leaching sphalerite-MnO 2 in the presence and absence of Acidithiobacillus thiooxidans ( A. thiooxidans). The polarization of anode and cathode, and the relationship between the electric quantity ( Q) and some factors, such as the dissolved rate of Zn 2+ and Fe 2+, and the time in the bio-electro-generating simultaneous leaching (BEGL) and electro-generating simultaneous leaching (EGL) were studied. A three-electrode system was applied to studying anodic and cathodic self-corrosion current, which was inappreciable compared with the galvanic current between sphalerite and MnO 2. The results show that the dissolved Zn 2+ in the presence of A. thiooxidans is nearly 43% higher than that in the absence of A. thiooxidans; the electrogenerative quantity in the former is about 150% more than that in the latter. The accumulated sulfur on the surface of sulfides produced in the electrogenerative leaching process can be oxidized in the presence of A. thiooxidans, and the ratio of biologic electric quantity reaches 27.9% in 72 h.

Mechanism of electro-generative-leaching of chalcopyrite-MnO 2 in presence of Acidithiobacillus ferrooxidans

To clarify the role and mechanism of Acidithiobacillus ferrooxidans ( A. ferrooxidans) in bio-electro-generative-leaching (BEGL), an experiment was made on the electro-generative leaching of chalcopyrite -MnO 2 in the presence of the bacteria which grew respectively in Fe(II) and S 0 media. A dual cell system with chalcopyrite anode and MnO 2 cathode was used to study the relationship between time and both of electric quantity and dissolved rate of the two minerals in BEGL. The results show that the dissolved rates for Cu 2+ and Fe 2+ under the action of the bacteria cultivated by S 0 medium are almost 2 times faster than those by Fe(II). And the leaching ratio for Mn 2+ and the electric output increase by near 3 times. The oxidation residue of chalcopyrite was characterized by SEM and XRD, whose patterns are similar to those of raw ore in BEGL. The mechanism of anodic reaction for CuFeS 2-MnO 2 leaching in the presence of A. ferrooxidans cultivated by S 0 medium is proposed as a successive reaction of two independent sub-processes. The first stage is the dissolution of chalcopyrite to produce Cu 2+, Fe 2+ and sulfur, and the second stage is bio-oxidation of sulfur, which is the control step of the process. However, dissolution of MnO 2 lasts until the reaction of chalcopyrite stops or the ores exhaust in two types of leaching.

Robust Functional Vascular Network Formation In Vivo by Cooperation of Adipose Progenitor and Endothelial Cells

Rapid induction and maintenance of blood flow through new vascular networks is essential for successfully treating ischemic tissues and maintaining function of engineered neo-organs. We have previously shown that human endothelial progenitor cells (EPCs) form functioning vessels in mice, but these are limited in number and persistence; and also that human adipose stromal cells (ASCs) are multipotent cells with pericytic properties which can stabilize vascular assembly in vitro. In this study, we tested whether ASCs would cooperate with EPCs to coassemble vessels in in vivo implants. Collagen implants containing EPCs, ASCs, or a 4:1 mixture of both were placed subcutaneously into NOD/SCID mice. After a range of time periods, constructs were explanted and evaluated with regard to vascular network assembly and cell fate; and heterotypic cell interactions were explored by targeted molecular perturbations. The density and complexity of vascular networks formed by the synergistic dual-cell system was many-fold higher than found in implants containing either ASCs or EPCs alone. Coimplantation of ASCs and EPCs with either pancreatic islets or adipocytes produced neoorgans populated by these parenchymal cells, as well as by chimeric human vessels conducting flow. This study is the first to demonstrate prompt and consistent assembly of a vascular network by human ASCs and endothelial cells and vascularization by these cells of parenchymal cells in implants. Mixture of these 2 readily available, nontransformed human cell types provides a practical approach to tissue engineering, therapeutic revascularization, and in vivo studies of human vasculogenesis.

Electrogenerative leaching for sphalerite-MnO2 in the presence of Acidithiobacillus ferrooxidans

A dual cell system was used to study the electrogenerative leaching sphalerite-MnO2 under the conditions of presence and absence of Acidithiobacillus ferrooxidans (A. ferrooxidans). The polarization of anode and cathode, and the relationship between the electric quantity (Q) and some factors, such as the dissolved Zn2+, Fe2+, the time in the bio-electro-generating simultaneous leaching (BEGSL) and electro-generating simultaneous leaching (EGSL), were studied.

Mechanism of electro-generating leaching of chalcopyrite-MnO 2 in presence of Acidithiobacillus thiooxidans

A dual cell system with chalcopyrite anode and MnO 2 cathode was used to study the relations between time and such data as the electric quantity and the dissolution rates of the two minerals in the electro-generating leaching(EGL) and the bio-electro-generating leaching(BEGL), respectively. The results showed that the dissolution rates for Cu 2+ and Fe 2+ in BEGL were almost 2 times faster than those in EGL, and nearly 3 times for Mn 2+; the electric output increased nearly by 3 times. The oxidation residue of chalcopyrite was represented by TEM and XRD, whose pattern was similar to that of the raw ore in EGL. The mechanism for leaching of CuFeS 2-MnO 2 in the presence of Acidithiobacillus thiooxidans was proposed as a successive reaction of two independent sub-processes for the anode. The first stage, common to both processes, is dissolution of chalcopyrite to produce Cu 2+, Fe 2+ and sulfur. The second stage is subsequent oxidization of sulfur only in BEGL, which is the controlling step of the process. However, the dissolution of MnO 2 lasts until the reaction of chalcopyrite stops or the ores exhaust in two types of leaching.

Phosphorothioate-Stimulated Cellular Uptake of siRNA: A Cell Culture Model for Mechanistic Studies

The phosphorothioate(PS)-stimulated cellular uptake of naked short interfering RNA (siRNA) into mammalian cells indicates a promising new mechanistic strategy because it makes use of a caveosomal, rather than an endosomal pathway, which is used by the majority of known delivery systems. This PS-stimulated mode delivers large amounts of siRNA primarily into the perinuclear space which is related to measurable though moderate target suppression. The observed limited efficacy seems to be related to intracellular trapping of siRNA. Here, we studied the intracellular localisation of siRNA and Argonaute 2 (Ago2), the major component of the RNA interference (RNAi) machinery, by density gradient centrifugation and fluorescence microscopy after PS-stimulated delivery or transfection with Lipofectamine 2000. The two cell lines ECV-304 and SKRC-35 both take up siRNA in the PS-stimulated mode but only ECV-304 shows RNAi, i.e. siRNA-mediated suppression of lamin A/C expression, whereas SKRC-35 does not. This lack of RNAi in the latter cell line seems to be due to a block of an intracellular siRNA translocation process. This study provides strong evidence for the view that co-localisation of siRNA and Ago2 in the vicinity of the rough endoplasmic reticulum (rER) in ECV-304 cells is related to target inhibition, whereas density gradient fractionation of cell organelles shows a lack of co-localisation in SKRC-35 cells in which RNAi does not occur after the PS-mediated delivery. In summary, we propose to exploit this dual cell system to identify important steps of intracellular trafficking of siRNA after PS mediated delivery that are crucial for its biological activity and which seem to be of general importance for the understanding of the intracellular trafficking and release of siRNA.

Electro-generative mechanism for simultaneous leaching of pyrite and MnO2 in presence of A. ferrooxidans

A dual cell system was used to study the output power, output voltage, galvanic polarization of anode and cathode, and the relationship between the electric quantity(Q) and some factors, such as the dissolved Fe2+ magnitude, the time in the electrogenerative simultaneous leaching with bacteria(BEGSL) and without bacteria(EGSL). A three-electrode system was adopted to study their individual self-corrosion current, which was smaller compared with the galvanic current. The results show that the output power and voltage in BEGSL are higher than those in EGSL. The accumulated sulfur on the surface of sulfides produced in BEGSL can be oxidized by A. ferrooxidans, and the ratio of biologic electric quantity reaches 51.50% in 72 h. The first stage both in EGSL and in BEGSL is the dissolution of pyrite on the surface to ferrous ion and sulfur element, which was oxidized by A. ferrooxidans in the further procedure.

Electrogenerative-leaching of mechanically activated galena

The electrogenerative-leaching of galena activated mechanically in planetary centrifugal mill were studied. A dual cell system was introduced to investigate the leaching process. The experimental results indicated that the mechanical activation improved the galena’s lattice constant, the lattice distortion and the degree of crystal defect, which resulted a decreasing of initial potential of galena electrode and an increasing of output voltage of the leaching cell.

Mechanism of influence of chloride ions on electrogenerative leaching of sulfide minerals

A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leaching system are similar, and chlorine ion is involved in the electrogenerative leaching process of sulfide minerals directly. The output power increases with the increase of Cl− concentration. The influence on the electrogenerative leaching rate decreases when the Cl− concentration reaches a certain value. The mechanisms of anodic reaction are deduced based on the reasonable hypothesis, and kinetic equations with respect to chlorine ions for each sulfide mineral are obtained. The kinetic equations show that when concentration of Cl− is relatively low, the electrogenerative leaching rates are predicted to have 2/5, 2/7, 1/3 and 1/3 order dependence on Cl− concentration for chalcopyrite concentrate, nickel concentrate, sphalerite and galena. As concentration of Cl− increases, the correlative dependence of electrogenerative leaching rate on concentration of Cl− becomes weak.

Mechanism of influence of ferric ion on electrogenerative leaching of sulfide minerals with FeCl 3

A dual cell system was used to study the influence of ferric ion on the electrogenerative leaching of sulfide minerals. Reaction mechanisms for the ferric chloride electrogenerative leaching of a series of sulfide minerals were proposed based on the data collected from the dual cell experiments. The influences of ferric ion on the electrogenerative leaching of sulfide minerals are similar. Ferric ion plays an important role on limiting the electrogenerative leaching rate at a relatively low concentration of FeCl 3 (about less than 0.15 mol/L). The mathematical models based on the Butler-Volmer relation were delineated, and kinetic equations with respect to ferric ions for each sulfide mineral were obtained. The kinetic equations show that when the concentration of ferric ion is relatively low, the electrogenerative leaching rates are predicted to be proportional to 6/7, 4/5, 2/3 and 2/3 order of ferric ion for nickel concentrate, chalcopyrite concentrate, sphalerite and galena respectively. As the concentration of ferric ion increase, the correlative dependence between electrogenerative leaching rate and concentration of ferric ion becomes weak. The above conclusions are in agreement with the experimental results.

Electrogenerative leaching of nickel sulfide concentrate with ferric chloride

In order to utilize the chemical energy in hydrometallurgical process of sulfide minerals reasonably and to simplify the purifying process, the electrogenerative process was applied and a dual cell system was introduced to investigate FeCl3 leaching of nickel sulfide concentrate. Some factors influencing the electrogenerative leaching, such as electrode structure, temperature and solution concentration were studied. The results show that a certain quantity of electrical energy accompanied with the leached products can be acquired in the electrogenerative leaching process. The output current and power increase with the addition of acetylene black to the electrode. Varying the components of electrode just affects the polarization degree of anode. Increasing FeCl3 concentration results in a sharp increase in the output of the leaching cell when c(FeCl3) is less than 0.1 mol/L. The optimum value of NaCl concentration for electrogenerative leaching nickel sulfide concentrate with FeCl3 is 3.0 mol/L. Temperature influences electrogenerative leaching by affecting anodic and cathodic polarization simultaneously. The apparent activation energy is determined to be 34. 63 kJ/mol in the range of 298 K to 322 K. The leaching rate of Ni2+ is 29.3% after FeCl3 electrogenerative leaching of nickel sulfide concentrate for 620 min with a filter bag electrode.